The present invention relates to novel compositions comprising polyalkylene succinimides and post-treated derivatives of polyalkylene succinimides. In a further aspect, the invention relates to methods of preparing these compositions and their uses as dispersants in lubricating oils and deposit inhibitors in hydrocarbon fuels. In another aspect, the invention relates to concentrates, lubricating oil compositions, and hydrocarbon fuel compositions containing such novel compositions.
Lubricating oil compositions for internal combustion engines generally contain a variety of additives to reduce or control deposits, wear, corrosion, etc. Similarly, liquid hydrocarbon fuels for internal composition engines, at a minimum, contain additives which control or reduce the formation of deposits. The present invention is concerned with compositions useful as dispersants or deposit inhibitors.
In lubricating oils, dispersants function to control sludge, carbon, and varnish produced primarily by the incomplete oxidation of the fuel, or impurities in the fuel, or impurities in the base oil used in the lubricating oil composition. Dispersants also control viscosity increase due to the presence of soot in diesel engine lubricating oils.
Deposit inhibitors in fuel control or reduce engine deposits also caused by incomplete combustion of the fuel. Such deposits can form on the carburetor parts, throttle bodies, fuel injectors, intake parts, and valves. Those deposits can present significant problems, including poor acceleration and stalling, and increased fuel consumption and exhaust pollutants.
One of the most effective class of lubricating oil dispersants and fuel deposit inhibitors are polyalkylene succinimides. In some cases, the succinimides have also been found to provide fluid-modifying properties, or a so-called viscosity index credit, in lubricating oil compositions. That results in a reduction in the amount of viscosity index improver which would be otherwise have to be used. A drawback of succinimide dispersants is that they have generally been found to reduce the life of fluorocarbon elastomers. In general, for a given succinimide dispersant, a higher nitrogen content gives better dispersancy but poorer fluorocarbon elastomer compatibility.
Therefore, as well as improving the dispersancy and VI credit properties of polyalkylene succinimides, it would be desirable to improve the fluorocarbon elastomer compatibility of such dispersants. It would further be desirable to improve the stability of polyalkylene succinimides, particularly hydrolytic stability and shear stress stability. It would also be desirable to improve soot dispersancy, especially where the lubricating oil is intended for use in diesel engine crankcases.
Polyalkylene succinimides are generally prepared by the reaction of the corresponding polyalkylene succinic anhydride with a polyalkyl polyamine. Polyalkylene succinic anhydrides are generally prepared by a number of well-known processes. For example, there is a well-known thermal process (see, e.g., U.S. Pat. No. 3,361,673), an equally well-known chlorination process (see, e.g., U.S. Pat. No. 3,172,892), a combination of the thermal and chlorination processes (see, e.g., U.S. Pat. No. 3,912,764), and free radical processes (see, e.g., U.S. Pat. Nos. 5,286,799 and 5,319,030). Such compositions include one-to-one monomeric adducts (see, e.g., U.S. Pat. Nos. 3,219,666 and 3,381,022), as well as xe2x80x9cmultiply adductedxe2x80x9d products, adducts having alkenyl-derived substituents adducted with at least 1.3 succinic groups per alkenyl-derived substituent (see, e.g., U.S. Pat. No. 4,234,435).
U.S. Pat. Nos. 3,361,673 and 3,018,250 describe the reaction of an alkenyl- or alkyl-substituted succinic anhydride with a polyamine to form alkenyl or alkyl succinimides lubricating oil dispersants and/or detergent additives.
U.S. Pat. No. 4,612,132 teaches that alkenyl or alkyl succinimides may be modified by reaction with a cyclic or linear carbonate or chloroformate such that one or more of the nitrogens of the polyamine moiety is substituted with a hydrocarbyl oxycarbonyl, a hydroxyhydrocarbyl oxycarbonyl, or a hydroxy poly(oxyalkylene) oxycarbonyl. These modified succinimides are described as exhibiting improved dispersancy and/or detergency in lubricating oils.
U.S. Pat. No. 4,747,965 discloses modified succinimides similar to those disclosed in U.S. Pat. No. 4,612,132, except that the modified succinimides is described as being derived from succinimides having an average of greater than 1.0 succinic groups per long chain alkenyl substituent.
The effect of the alkenyl-derived substituent""s molecular weight on the performance of succinimides as lubricating oil additives is described in xe2x80x9cThe Mechanism of Action of Polyisobutenyl Succinimide Lubricating Oil Additives,xe2x80x9d by E. S. Forbes and E. L. Neustadter (Tribology, Vol. 5, No. 2, pp. 72-77 (April, 1972)). This article discusses, in part, the effect of polyisobutenyl Mn on the detergency properties of a polyisobutenyl succinimide. However, as shown in FIG. 1 on page 76 of their article, the results of the tests Forbes and Neustadter conducted indicate that succinimides having a 1300 Mn polyisobutenyl substituent are more effective as detergents than those having a polyisobutenyl substituent with a Mn of 2000 or greater. In showing the effect of polyisobutenyl molecular weight on succinimide detergency, this article teaches that maximum detergency performance is obtained when the polyisobutenyl group has a Mn of about 1300.
A recent article by S. T. Roby, R. E. Kornbrekke, and J. A. Supp xe2x80x9cDeposit Formulation in Gasoline Engines, Part 2, Dispersant Effects on Sequence VE Depositsxe2x80x9d JOURNAL OF THE SOCIETY OF TRIBOLOGISTS AND LUBRICATION ENGINEERS, Vol. 50, 12, 989-995 (December 1994) teaches that the length of the dispersant alkyl side chain influences deposit control performance, and that, at the same nitrogen level, the low molecular weight (side chain 1000 daltons) dispersants that were tested were poorer than the tested high molecular weight (side chain 2000 daltons) succinimide dispersants. This teaching is also consistent with our prior observation comparing 950 Mn side chain succinimides with 2200 Mn side chain succinimides.
U.S. Pat. No. 4,234,435 teaches a preferred polyalkene-derived substituent group with a Mn in the range of 1500-3200. For polybutenes, an especially preferred Mn range is 1700-2400. This patent also teaches that the succinimides must have a succinic ratio of at least 1.3. That is, there should be at least 1.3 succinic groups per equivalent weight of polyalkene-derived substituent group. Most preferably, the succinic ratio should be from 1.5 to 2.5. This patent further teaches that its dispersants also provide an improvement in viscosity index. That is, these additives impart fluidity modifying properties to lubricant compositions containing them. This is considered desirable for use in multigrade lubricating oils but undesirable for single-grade lubricating oils.
Polyamino alkenyl or alkyl succinimides and other additives useful as dispersants and/or detergents, such as Mannich bases, contain basic nitrogen. While basicity is an important property to have in the dispersant/detergent additive, it is believed that the initial attack on fluorocarbon elastomer seals used in some engines involves attack by the basic nitrogen. This attack leads to the loss of fluoride ions, and eventually results in cracks in the seals and loss of other desirable physical properties in the elastomer.
A variety of post-treatments for improving various properties of alkenyl succinimides are known to the art, a number of which are described in U.S. Pat. No. 5,241,003.
Example 2 of U.S. Pat. No. 5,266,186 discloses the preparation of dispersants by reacting certain polyisobutenyl-succinic anhydride adducts (see footnote 2 of Table 2) with ethylenediamine, followed by reaction with a maleic anhydride/xcex1-olefin copolymer. The patent teaches that, by functioning as an iron sulfide dispersant, the product is useful to inhibit sludge deposits in refinery processing equipment caused by the heat treatment of hydrocarbon feed stocks.
U.S. Pat. No. 5,112,507 discloses a polymeric ladder type polymeric succinimide dispersant in which each side of the ladder is a long chain alkyl or alkenyl, generally having at least about 30 carbon atoms, preferably at least about 50 carbon atoms. The dispersant is described as having improved hydrolytic stability and shear stress stability, produced by the reaction of certain maleic anhydride-olefin copolymers with certain polyamines. The patent further teaches that the polymer may be post-treated with a variety of post-treatments, and describes procedures for post-treating the polymer with cyclic carbonates, linear mono- or polycarbonates; boron compounds (e.g., boric acid), and fluorophosphoric acid and ammonia salts thereof.
U.S. Pat. Nos. 5,334,321 and 5,356,552 disclose certain cyclic carbonate post-treated alkenyl or alkylsuccinimides having improved fluorocarbon elastomer compatibility, which are preferably prepared by the reaction of the corresponding substituted succinic anhydride with a polyamine having at least four nitrogen atoms per mole.
European Application, EP 0 682 102 A2 discloses a process which comprises reacting: a copolymer of an olefin and maleic anhydride, an acyclic hydrocarbyl-substituted succinic acylating agent, and an alkylene polyamine. These products are useful in lubricating oil compositions as additives for use as dispersants having viscosity index improver properties.
The present invention provides novel polymers comprising polyalkylene succinimides and post-treated derivatives thereof. These polymers, and in particular the post-treated derivatives, have excellent dispersant properties, improved hydrolytic and shear stress stability, and improved fluorocarbon elastomer compatibility. In a preferred embodiment the polymers are essentially chlorine-free.
The polyalkylene succinimides of the present invention can be prepared by the reaction of alkyl or alkenyl succinic acid derivatives with certain copolymers of an unsaturated acidic reagent (for example copolymers of unsaturated acidic reagents and xcex1-olefins) and a polyamine having at least three nitrogens per molecule. The xcex1-olefin moiety of the copolymer may also be substituted with various substituents, so long as the substituent does not interfere with the reaction or adversely affect performance of the product. Because of competing and sequential reactions, the reaction product will be a mixture of compounds, which function as dispersants. Thus, by varying the mole ratio of reactants, variations in the products, and correspondingly variations in the properties of product, can be obtained. The reaction product will be a mixture because all of the reactants are generally furnished commercially as mixtures.
It is believed that the improvement in properties is primarily due to the production of a new polyalkylene succinimide that can be represented by the following formula: 
wherein:
W is a nitrogen-containing group selected from the group consisting 
R is a polyalkyl or polyalkylene having a number average molecular weight of at least 1000 preferably from 1800 to 3000,
R1 is an alkyl having an average of from 12 to 28 carbon atoms;
Z is a polyalkylene polyamine linking radical;
m is a whole integer of from 1 to 3
n is a whole integer of from 1 to 3;
x is a whole integer of from 2 to 20;
Int. is an initiating radical;
Ter. is a terminating group; and
wherein R2and R3 are independently hydrogen, alkyl, phenyl, or taken together are alkylene to give a ring group.
The (Int.) and (Ter.) substituent are carried over into the present composition from the maleic anhydride reactant and are present in the copolymer reactants as a result of the free radical initiator used to prepare the copolymer. Typical (Int.) and (Ter.) group include 
wherein R5 is hydrogen, alkyl, aryl, alkaryl, cycloalkyl, alkoxy, cycloalkoxy, acyl, alkenyl, cycloalkenyl, alkynyl; or alkyl, aryl or alkaryl optionally substituted with 1 to 4 substituents independently selected from nitrile, keto, halogen, nitro, alkyl, aryl, and the like; and R6 and R7 are independently hydrogen, alkyl, aryl, alkaryl, and the like.
Typically the (Int.) group and (Ter.) group will be the same but may also be different because of secondary or competing reactions in the initial copolymerization or the subsequent reaction used to prepare the composition of the present invention; including, in some reaction with organic solvents such as toluene, resulting in a benzyl radical initiator or terminating group.
The corresponding post-treated derivative can be obtained by treating the reaction product with the desired post-treatment. For example, the reaction product is preferably treated with a cyclic carbonate, preferably ethylene carbonate, preferably by the procedure described in U.S. Pat. Nos. 4,612,132 and 5,334,321 hereby incorporated by reference.
The present invention further provides lubricating oil compositions comprising a major amount of a base oil of lubricating viscosity and a minor amount of the compounds of the invention (xe2x80x9cactive ingredientsxe2x80x9d). The active ingredients can be applied at effective amounts, which are highly effective to control engine sludge and varnish and yet be compatible with fluorocarbon elastomer engine seals. The invention also provides a concentrate comprising about 20 to 60 wt. % of the compounds or compound mixtures and about 40 to 80 wt. % of a compatible liquid diluent designed to be added directly to a base oil. Both the lubricating oil composition and concentrate may also contain other additives designed to improve the properties of the base oil, including other detergent-dispersants.
The present invention further provides a fuel composition comprising a major amount of hydrocarbons boiling in the gasoline or diesel range and from 10 to 10,000 parts per million parts of the hydrocarbon of a compound or mixture of compounds of the present invention.
The composition of the present invention can be prepared reacting a mixture under reactive conditions, wherein the mixture comprises:
(a) an alkenyl or alkylsuccinic acid derivative, wherein the alkenyl or alkyl substituent has a Mn of from 1800 to 3000;
(b) an unsaturated acidic reagent copolymer of
(1) an unsaturated acidic reagent and
(2) an olefin having an average of from 14 to 30 carbon atoms, wherein the copolymer has a Mn of from 2000 to 4800; and
(c) a polyamine having at least three nitrogen atoms and 4 to 20 carbon atoms.
The mixture contains about from 1.5 to 10 equivalents of the alkenyl or alkylsuccinic acid derivative per equivalent of the unsaturated acidic reagent copolymer and about from 0.4 to 1.0 moles of the polyamine per equivalent of alkenyl or alkylsuccinic acid derivative plus unsaturated acidic reagent copolymer. Preferably, the acid derivative is an anhydride, and the unsaturated acidic reagent copolymer is a copolymer of maleic anhydride and an olefin, and the polyamine has at least six nitrogen atoms per mole.
Additional aspects of the invention will be apparent from the following detailed description.
In its broadest aspect, the present invention involves a polymer having the general formula: 
wherein:
W is a nitrogen-containing group selected from the group consisting 
R is a polyalkyl or polyalkylene having a number average molecular weight of from 1800 to 3000,
R1 is an alkyl having an average of from 12 to 28 carbon atoms;
Z is a polyalkylene polyamine linking radical;
m is a whole integer of from 1 to 3
n is a whole integer of from 1 to 3;
x is a whole integer of from 2 to 20;
Int. is an initiating radical;
Ter. is a terminating group; and
wherein R2 and R3 are independently hydrogen, alkyl, phenyl, or taken together are alkylene to give a ring group.
In simplified terms, the compound of formula (I), shown above, can be considered a polyalkylene succinimide produced by the reaction of a copolymer (the unsaturated acidic reagent copolymer) with a monomer (the alkene or alkyl succinic acid derivative) in which the monomer is linked to the polymer units by a polyamine linking group. Because the polyalkylene succinimide mixture contains about from 1.5 to 10 equivalents of alkenyl or alkylsuccinic acid derivative per equivalent of unsaturated acidic reagent copolymer, and about from 0.4 to 1.0 equivalents of polyamine per equivalent of alklenyl or alkylsuccinic acid derivative plus unsaturated acidic reagent copolymer, other structures, such as (II) and (III), shown below, can also be present, depending on the ratios of alkenyl or alkylsuccinic acid derivative, unsaturated acidic reagent copolymer, and polyamine. 
wherein W, R, R1, R2, and R3, Z, m, n, x, Int., Ter are the same as described above.
In addition to the predominant polymer of formula (I), (II), or (III), the reaction will typically contain more complex reaction products and polymers because of competing and sequential reactions, and because the alkenyl or alkylsuccinic acid derivative might contain more than one succinic anhydride moiety per long chain alkyl or alkenyl group or contain unsaturated acidic reagent oligomers.
Referring to formulas (I), (II), and (III), the preferred compounds or compound mixtures are those wherein Z is a polyamino radical having about from 3 to 7, more preferably, about 4 to 5 nitrogen atoms and 8 to 20 carbon atoms.
The initiating group and terminating group will be a function of the initiator used to initiate the free radical reaction used to prepare the copolymer and may vary with the particular copolymer and secondary reactions. Discounting secondary reactions, the preferred Int. and Ter. groups are where R1 is a preferred alkyl group are 
As used herein the following terms have the following meanings, unless expressly stated to the contrary.
The term xe2x80x9csuccinimidexe2x80x9d is understood in the art to include many of the amide, imide, etc. species which are also formed by the reaction of a succinic anhydride with an amine. The predominant product, however, is succinimide and this term has been generally accepted as meaning the product of a reaction of an alkenyl- or alkyl-substituted succinic acid or anhydride with a polyamine. Alkenyl or alkyl succinimides are disclosed in numerous references and are well known in the art. Certain fundamental types of succinimides and related materials encompassed by the term of art xe2x80x9csuccinimidexe2x80x9d are taught in U.S. Pat. Nos. 2,992,708; 3,018,291; 3,024,237; 3,100,673; 3,219,666; 3,172,892; and 3,272,746, the disclosures of which are hereby incorporated by reference.
The term xe2x80x9cTotal Base Numberxe2x80x9d or xe2x80x9cTBNxe2x80x9d refers to the amount of base equivalent to milligrams of KOH in 1 gram of sample. Thus, higher TBN numbers reflect more alkaline products and therefore a greater alkalinity reserve. The TBN of a sample can be determined by ASTM Test No. D2896 or any other equivalent procedure.
The term xe2x80x9cSAPxe2x80x9d refers to Saponification Number and can be determined by the procedure described in ASTM D94 or any other equivalent procedure.
The term xe2x80x9cTANxe2x80x9d refers to Total Acid Number and can be determined by the procedure described in ASTM D 664 or any other equivalent procedure.
The xe2x80x9csuccinic ratioxe2x80x9d or xe2x80x9csuccination ratioxe2x80x9d refers to the ratio calculated in accordance with the procedure and mathematical equation set forth in columns 5 and 6 of U.S. Pat. No. 5,334,321, hereby incorporated by reference. The calculation is asserted to represent the average number of succinic groups in an alkenyl or alkylsuccinic anhydride per alkenyl or alkyl chain.
The term xe2x80x9cPIBSAxe2x80x9d means polyisobutenyl succinic anhydride.
The term xe2x80x9chydrocarbon soluble compatible saltxe2x80x9d refers to a salt which is soluble in an oil of lubricating viscosity or a hydrocarbon fuel suitable for use in spark-ignition or diesel engines and which is compatible with such composition.
The term xe2x80x9calkenyl or alkylsuccinic acid derivativexe2x80x9d refers to a structure having the formula 
wherein L and M are independently selected from the group consisting of xe2x80x94OH, xe2x80x94Cl, xe2x80x94Oxe2x80x94, lower alkyl or taken together are xe2x80x94Oxe2x80x94 to form an alkenyl or alkylsuccinic anhydride group.
The term xe2x80x9cunsaturated acidic reagentxe2x80x9d refers to maleic or fumaric reactants of the general formula: 
wherein X and Xxe2x80x2 are the same or different, provided that at least one of X and Xxe2x80x2 is a group that is capable of reacting to esterify alcohols, form amides, or amine salts with ammonia or amines, form metal salts with reactive metals or basically reacting metal compounds and otherwise function as acylating agents. Typically, X and/or Xxe2x80x2 is xe2x80x94OH, xe2x80x94O-hydrocarbyl, xe2x80x94OM+ where M+ represents one equivalent of a metal, ammonium or amine cation, xe2x80x94NH2, xe2x80x94Cl, xe2x80x94Br, and taken together X and Xxe2x80x2 can be xe2x80x94Oxe2x80x94 so as to form an anhydride. Preferably, X and Xxe2x80x2 are such that both carboxylic functions can enter into acylation reactions. Maleic anhydride is a preferred unsaturated acidic reactant. Other suitable unsaturated acidic reactants include electron-deficient olefins such as monophenyl maleic anhydride; monomethyl, dimethyl, monochloro, monobromo, monofluoro, dichloro and difluoro maleic anhydride, N-phenyl maleimide and other substituted maleimides; isomaleimides; fumaric acid, maleic acid, alkyl hydrogen maleates and fumarates, dialkyl fumarates and maleates, fumaronilic acids and maleanic acids; and maleonitrile, and fumaronitrile.
The compounds of the present invention can be prepared by contacting the desired alkyl or alkenyl succinic acid derivative with an unsaturated acidic reagent copolymer and polyamine under reactive conditions: 
wherein R, R1, Z, L, M, n, (Int) and (Ter) are as defined above.
Typically the above process is conducted by contacting from 1.5 to 10 equivalents of alkenyl or alkylsuccinic acid derivative (A) per mole of unsaturated acidic reagent copolymer (B) and from 0.4 to 1.0 equivalents of amine (C) per equivalent of alkenyl or alkylsuccinic acid derivative (A) plus unsaturated acidic reagent copolymer (B). In conducting this reaction we have generally found it convenient to first add the alkenyl or alkylsuccinic acid derivative and the unsaturated acidic reagent copolymer together and then add the polyamine. It may be desirable to conduct the reaction in an inert organic solvent. Optimum solvents will vary with the particular copolymer and can be determined from literature sources or routine experimentations. For example, in the case of maleic anhydride poly xcex1-olefin copolymers, we found that 100N diluent oil and mixtures of C9 aromatic solvents are acceptable solvents.
We have found that when less than 1.5 equivalents of alkenyl or alkylsuccinic acid derivative (A) per mole of unsaturated acidic reagent copolymer (B) are used then the polymer sometimes contains gels, which is undesirable.
Typically, the reaction is conducted at temperatures in the range of about from 140 to 180xc2x0 C., preferably 150 to 170xc2x0 C. for about from 1 to 10 hours, preferably 4 to 6 hours. Typically the reaction is conducted at about atmospheric pressure; however, higher or lower pressures can also be used depending on the reaction temperature desired and the boiling point of the reactants or solvent.
As above noted, the reaction product will typically be a mixture, both because of the secondary products or byproducts and also because the reactants will typically be mixtures. In theory, pure compounds could be obtained, for example by using pure compounds as reactants and then separating out the desired pure compounds from the reaction product. However, commercially, the expense of this would rarely be justified and accordingly the commercial product will generally be a mixture in which formulas (I), (II), and (III) will be the predominant compounds.
Water, present in the system or generated by the reaction of the amine with the succinic or maleic anhydride moieties of (A) and (B) alkyl succinimide, is preferably removed from the reaction system during the course of the reaction via azeotroping or distillation. After reaction completion, the system can be stripped at elevated temperatures (typically 100xc2x0xe2x96xa1 C. to 250xc2x0xe2x96xa1 C.) and reduced pressures to remove any volatile components which may be present in the product.
Alkyl and alkenylsuccinic acid derivatives having a calculated succinic ratio of about from 1:1 to 2.5:1, and preferably about from 1:1 to 1.5:1, may be used in the present process. More preferably, the alkyl or alkenyl succinic acid derivatives have a succination ratio of about from 1:1 to 1.2:1. Most preferably, alkyl or alkenylsuccinic anhydrides are used. Accordingly we prefer to use alkenyl succinic anhydride prepared by the thermal process, both because the calculated succination ratio of material prepared by this process is typically 1.0 to 1.2, and because the produce is essentially chlorine-free because chlorine is not used in the synthesis.
The thermal reaction of a polyolefin with maleic anhydride is well known and is described, for example, in U.S. Pat. No. 3,361,673. The less desirable is the chlorination process characterized by the reaction of a chlorinated polyolefin, with maleic anhydride, which is also well known and is described, for example, in U.S. Pat. No. 3,172,189. Various modifications of the thermal process and chlorination process are also well known, some of which are described in U.S. Pat. Nos. 4,388,471; 4,450,281; 3,018,250 and 3,024,195. Free radical procedures for preparing alkenyl succinic anhydrides are, for example, described in U.S. Pat. Nos. 5,286,799 and 5,319,030. All of the above referenced patents are hereby incorporated herein by reference in their entirety.
In accordance with the invention, the alkenyl or alkyl succinic anhydride reactant is derived from a polyolefin having a Mn from 1000 to 5000 and a Mw/Mn ratio of 1:1 to 5:1. In a preferred embodiment, the alkenyl or alkyl group of the succinimide has a Mn value from 1800 to 3000. Most preferred are alkenyl or alkyl substituents having a Mn of from 2000 to 2500.
Suitable polyolefin polymers for reaction with maleic anhydride include polymers comprising a major amount of C2 to C5 monoolefin, e.g., ethylene, propylene, butylene, iso-butylene and pentene. The polymers can be homopolymers, such as polyisobutylene, as well as copolymers of two or more such olefins, such as copolymers of: ethylene and propylene, butylene, and isobutylene, etc. Other copolymers include those in which a minor amount of the copolymer monomers (e.g., 1 to 20 mole percent), is a C4 to C8 nonconjugated diolefin, e.g., a copolymer of isobutylene and butadiene or a copolymer of ethylene, propylene and 1,4-hexadiene, etc.
A particularly preferred class of olefin polymers for reaction with maleic anhydride comprises the polybutenes, which are prepared by polymerization of one or more of 1-butene, 2-butene and isobutene. Especially desirable are polybutenes containing a substantial proportion of units derived from isobutene. The polybutene may contain minor amounts of butadiene, which may or may not be incorporated in the polymer. These polybutenes are readily available commercial materials well known to those skilled in the art. Examples of procedures illustrating the preparation of such material can be found, for example, in U.S. Pat. Nos. 3,215,707; 3,231,587; 3,515,669; 3,579,450; 3,912,764 and 4,605,808, hereby incorporated by reference for their disclosures of suitable polybutenes.
The alkenyl or alkylsuccinic anhydride may also be prepared using the so-called highly reactive or high methyl vinylidene polyalkylene, most commonly polyisobutene, such as described in U.S. Pat. Nos. 4,152,499; 5,071,919; 5,137,980; 5,286,823; 5,254,649; published International Applications Numbers WO 93 24539-A1; WO 9310063-A1; and published European Patent Applications Numbers 0355895-A; 0565285A; and 0587381A, all of which are hereby incorporated by reference in their entirety. Other polyalkenes can also be used including, for example, polyalkenes prepared using metallocene catalysts such as for example described in published German patent application DE 4313088A1.
The unsaturated acidic reagent copolymers used in the present invention can be random copolymers or alternating copolymers, and can be prepared by known procedures. Further, in most instances, examples of each class are readily commercially available. Such copolymers may be prepared by the free radical reaction of an unsaturated acidic reagent with the corresponding monomer of the other unit of the copolymer. Thus, in the present case, the monomer will correspond to R1 in formula (I) plus a vinyl group, i.e., R1xe2x80x94CH=CH2. Hence, where R1 is phenyl the monomer will be styrene. Accordingly, the unsaturated acidic reagent copolymer can be prepared by the free radical reaction of an unsaturated acidic reagent, preferably maleic anhydride, with the corresponding C8 to C48 xcex1-olefin, C8 to C28 polyalkylene, ethylene, styrene, 1,3-butadiene, C3+ vinyl alkyl ether, or C4+ vinyl alkanoate.
We prefer to use alpha olefins from C12 to C28 because these materials are commercially readily available, and because they offer a desirable balance of the length of the molecular weight tail, and the solubility of the copolymer in non polar solvents. Mixtures of olefins, eg C14, C16, and C18 are especially desirable.
The degree of polymerization of the copolymers can vary over a wide range. In general copolymers of high molecular weight can be produced at low temperatures and copolymers of low molecular weight can be produced at high temperatures. It has been generally shown that for the polymers of this invention, we prefer low molecular weight copolymers, i.e., low molecular weight (2000-5500 for example) because higher molecular weight copolymers (greater than 10,000 for example) can sometimes produce polymers that contain gels.
The copolymerization is conducted in the presence of a suitable free radical initiator; typically a peroxide type initiator, e.g. di(t-butyl) peroxide dicumyl peroxide or azo type initiator, e.g., isobutylnitrile type initiators. Procedures for preparing poly xcex1-olefin copolymers are, for example, described in U.S. Pat. Nos. 3,560,455 and 4,240,916, hereby incorporated by reference in their entirety. Both patents also describe a variety of initiators.
Some examples of maleic anhydride xcex1-olefin copolymers are:
Poly(styrene-co-maleic anhydride) resins: These materials are known as SMA(copyright) resins. There are two molecular weight versions. The low molecular weight resin is called SMA resin and is available from ARCO Chemical with styrene to maleic anhydride ratio""s of 1:1, 2:1, and 3:1. The high molecular weight resin is produced by Monsanto (Lytron(copyright)), ARCO (Dylark(copyright)) or American Cyanamide (Cypress(copyright)). Other names for SMA copolymers are Styrolmol, Maron MS, and Provimal ST resins. In some cases partially esterified resins are also available.
Poly(ethylene-co-maleic anhydride) resins: These materials are manufactured by Monsanto under the trade name EMA(copyright). They are also called Malethamer and Vinac resins.
Poly(alpha olefin-co-maleic anhydride) resins are available from Chevron Chemical as PA-18 (octadecene-1-co-maleic anhydride), or can be prepared as in Preparation 1. Alternately mixtures of alpha olefins can be used. These materials have been described in U.S. Pat. Nos. 3,461,108; 3,560,455; 3,560,456; 3,560,457; 3,580,893; 3,706,704; 3,729,450; and 3,729,451. Partially esterified olefin co maleic anhydride resins can also be used. Some examples of these types of resins are called Ketjenlube(copyright) resins available from AKZO Co.
Poly(isobutene-co-maleic anhydride) resins are called ISOBAM(copyright) and are manufactured by Curaray Co. Ltd. They are also available from Humphrey chemical Co. under the code K-66.
Poly(butadiene-so-maleic anhydride) resins are called Maldene(copyright) and are made by Borg-Warner Corp.
Poly(methylvinylether-co-maleic anhydride) resins are sold by GAF Corporation under the name Gantrey An. Other names are called Visco Frey.
Poly(vinylacetate-co-maleic anhydride) resins are available from Monsanto and are called Lytron 897, 898, and 899. They are also called Pouimalya resins in Europe.
We have found that excellent results can be obtained using a copolymer prepared by the free radical polymerization of maleic anhydride and C12 to C18 xcex1-olefins or olefin mixtures thereof.
The polyamine reactant should have at least three amine nitrogen atoms per mole, and preferably 4 to 12 amine nitrogens per molecule. Most preferred are polyamines having from about 6 to about 10 nitrogen atoms per molecule. The number of amine nitrogen atoms per molecule of polyamine is calculated as follows:                               Average          ⁢                      xe2x80x83                    ⁢          number          ⁢                      xe2x80x83                    ⁢          of          ⁢                      xe2x80x83                    ⁢          nitrogen                                              atoms          ⁢                      xe2x80x83                    ⁢          in          ⁢                      xe2x80x83                    ⁢          molecule          ⁢                      xe2x80x83                    ⁢          of          ⁢                      xe2x80x83                    ⁢          polyamine                      =            %      ⁢              xe2x80x83            ⁢      N      xc3x97              M        pa                    14      xc3x97      100      
wherein
% N=percent nitrogen in polyamine or polyamine mixture
Mpa=number average molecular weight of the polyamine or polyamine mixture
Preferred polyalkylene polyamines also contain from about 4 to about 20 carbon atoms, there being preferably from 2 to 3 carbon atoms per alkylene unit. The polyamine preferably has a carbon-to-nitrogen ratio of from 1:1 to 10:1.
Examples of suitable polyamines that can be used to form the compounds of this invention include the following: tetraethylene pentamine, pentaethylene hexamine, Dow E-100(copyright) heavy polyamine (number average Mw=303, available from Dow Chemical Company, Midland, Mich.), and Union Carbide HPA-X heavy polyamine (number average Mw=275, available from Union Carbide Corporation, Danbury, Conn.). Such amines encompass isomers, such as branched-chain polyamines, and the previously mentioned substituted polyamines, including hydrocarbyl-substituted polyamines. HPA-X heavy polyamine (xe2x80x9cHPA-Xxe2x80x9d) contains an average of approximately 6.5 amine nitrogen atoms per molecule. Such heavy polyamines generally afford excellent results.
The polyamine reactant may be a single compound but typically will be a mixture of compounds reflecting commercial polyamines. Typically the commercial polyamine will be a mixture in which one or several compounds predominate with the average composition indicated. For example, tetraethylene pentamine prepared by the polymerization of aziridine or the reaction of dichloroethylene and ammonia will have both lower and higher amine members, e.g., triethylene tetramine (xe2x80x9cTETAxe2x80x9d), substituted piperazines and pentaethylene hexamine, but the composition will be largely tetraethylene pentamine and the empirical formula of the total amine composition will closely approximate that of tetraethylene pentamine.
Other examples of suitable polyamines include admixtures of amines of various sizes, provided that the overall mixture contains at least 4 nitrogen atoms per molecule. Included within these suitable polyamines are mixtures of diethylene triamine (xe2x80x9cDETAxe2x80x9d) and heavy polyamine. A preferred polyamine admixture reactant is a mixture containing 20% by weight DETA and 80% by weight HPA-X; as determined by the method described above, this preferred polyamine reactant contains an average of about 5.2 nitrogen atoms per mole.
Methods of preparation of polyamines and their reactions are detailed in Sidgewick""s THE ORGANIC CHEMISTRY OF NITROGEN, Clarendon Press, Oxford, 1966; Noller""s CHEMISTRY OF ORGANIC COMPOUNDS, Saunders, Philadelphia, 2nd Ed., 1957; and Kirk-Othmer""s ENCYCLOPEDIA OF CHEMICAL TECHNOLOGY, 2nd Ed., especially Volumes 2, pp. 99-116.
We have found that the dispersancy of the present polymers is generally further improved by reaction with a cyclic carbonate. This may result in some reduction in fluorocarbon elastomer compatibility. However, this generally can be most than offset by reducing the concentration of the carbonated post-treated polymer in light of the increased dispersancy. The cyclic carbonate post-treatment is especially advantageous where the dispersant will be used in engines which do not have fluorocarbon elastomer seals. The resulting modified polymer has one or more nitrogens of the polyamino moiety substituted with a hydroxy hydrocarbyl oxycarbonyl, a hydroxy poly(oxyalkylene)oxycarbonyl, a hydroxyalkylene, hydroxyalkylenepoly-(oxyalkylene), or mixture thereof.
The cyclic carbonate post-treatment is conducted under conditions sufficient to cause reaction of the cyclic carbonate with secondary amino group of the polyamino substituents. Typically, the reaction is conducted at temperatures of about from 0xc2x0 C. to 250xc2x0 C. preferably about from 100xc2x0 C. to 200xc2x0 C. Generally, best results are obtained at temperatures of about from 150xc2x0 C. to 180xc2x0 C.
The reaction may be conducted neat, wherein both the polymer and the cyclic carbonate are combined in the proper ratio, either alone or in the presence of a catalyst (such as an acidic, basic or Lewis acid catalyst). Depending on the viscosity of the polymer reactant, it may be desirable to conduct the reaction using an inert organic solvent or diluent, for example, toluene, xylene. Examples of suitable catalysts include, for example, phosphoric acid, boron trifluoride, alkyl or aryl sulfonic acid, alkali or alkaline carbonate. Generally, the same solvents or diluents as described above with respect to the preparation for the co-polymer (A) or polymer (I) can also be used in the cyclic carbonate post-treatment.
The reaction of polyamino alkenyl or alkyl succinimides with cyclic carbonates is known in the art and is described in U.S. Pat. No. 4,612,132, hereby incorporated by reference, in its entirety. Generally, the procedures described to post-treat polyamino alkenyl or alkyl succinimides with cyclic carbonates can also be applied to post-treat the present polymers.
A particularly preferred cyclic carbonate is 1,3-dioxolan-2-one (ethylene carbonate) because it affords excellent results and also because it is readily commercially available.
The molar charge of cyclic carbonate employed in the post-treatment reaction is preferably based upon the theoretical number of basic nitrogens contained in the polyamino substituent of the succinimide. Thus, when one equivalent of tetraethylene pentamine (xe2x80x9cTEPAxe2x80x9d) is reacted with one equivalent of succinic anhydride and one equivalent of copolymer, the resulting bis succinimide will theoretically contain 3 basic nitrogens. Accordingly, a molar charge of 2 would require that two moles of cyclic carbonate be added for each basic nitrogen or in this case 6 moles of cyclic carbonate for each mole equivalent of polyalkylene succinimide or succinimide prepared from TEPA. Mole ratios of the cyclic carbonate to the basic amine nitrogen of the polyamino alkenyl succinimide employed in the process of this invention are typically in the range of from about 1:1 to about 4:1; although preferably from about 2:1 to about 3:1.
As described in U.S. Pat. No. 4,612,132, cyclic carbonates may react with the primary and secondary amines of a polyamino alkenyl or alkyl succinimide to form two types of compounds. In the first instance, strong bases, including unhindered amines such as primary amines and some secondary amines, react with an equivalent of cyclic carbonate to produce a carbamic ester. In the second instance, hindered bases, such as hindered secondary amines, may react with an equivalent of the same cyclic carbonate to form a hydroxyalkyleneamine linkage. (Unlike the carbamate products, the hydroxyalkyleneamine products retain their basicity.) Accordingly, the reaction of a cyclic carbonate may yield a mixture of products. When the molar charge of the cyclic carbonate to the basic nitrogen of the succinimide is about 1 or less, a large portion of the primary and secondary amines of the succinimide will be converted to hydroxy hydrocarbyl carbamic esters with some hydroxyhydrocarbylamine derivatives also being formed. As the mole ratio is raised above 1 increased amounts of poly(oxyalkylene) polymers of the carbamic esters and the hydroxyhydrocarbylamine derivatives are produced.
Both the polymers and post-treated polymers of this invention can also be reacted with boric acid or a similar boron compound to form borated dispersants having utility within the scope of this invention. In addition to boric acid (boron acid), examples of suitable boron compounds include boron oxides, boron halides and esters of boric acid. Generally from about 0.1 equivalents to 10 equivalents of boron compound to the modified succinimide may be employed.
In addition to the carbonate and boric acids post-treatments both the compounds may be post-treated, or further post-treatment, with a variety of post-treatments designed to improve or impart different properties. Such post-treatments include those summarized in columns 27-29 of U.S. Pat. No. 5,241,003, hereby incorporated by reference. Such treatments include, treatment with:
Inorganic phosphorous acids or anhydrates (e.g., U.S. Pat. Nos. 3,403,102 and 4,648,980);
Organic phosphorous compounds (e.g., U.S. Pat. No. 3,502,677);
Phosphorous pentasulfides;
Boron compounds as already noted above (e.g., U.S. Pat. Nos. 3,178,663 and 4,652,387);
Carboxylic acid, polycarboxylic acids, anhydrides and/or acid halides (e.g., U.S. Pat. Nos. 3,708,522 and 4,948,386);
Epoxides polyepoxiates or thioexpoxides (e.g., U.S. Pat. Nos. 3,859,318 and 5,026,495);
Aldehyde or ketone (e.g., U.S. Pat. No. 3,458,530);
Carbon disulfide (e.g., U.S. Pat. No. 3,256,185);
Glycidol (e.g., U.S. Pat. No. 4,617,137);
Urea, thourea or guanidine (e.g., U.S. Pat. Nos. 3,312,619; 3,865,813; and British Patent GB 1,065,595);
Organic sulfonic acid (e.g., U.S. Pat. No. 3,189,544 and British Patent GB 2,140,811);
Alkenyl cyanide (e.g., U.S. Pat. Nos. 3,278,550 and 3,366,569);
Diketene (e.g., U.S. Pat. No. 3,546,243);
A diisocyanate (e.g., U.S. Pat. No. 3,573,205);
Alkane sultone (e.g., U.S. Pat. No. 3,749,695);
1,3-Dicarbonyl Compound (e.g., U.S. Pat. No. 4,579,675);
Sulfate of alkoxylated alcohol or phenol (e.g., U.S. Pat. No. 3,954,639);
Cyclic lactone (e.g., U.S. Pat. Nos. 4,617,138; 4,645,515; 4,668,246; 4,963,275; and 4,971,711);
Cyclic carbonate or thiocarbonate linear monocarbonate or polycarbonate, or chloroformate (e.g., U.S. Pat. Nos. 4,612,132; 4,647,390; 4,648,886; 4,670,170);
Nitrogen-containing carboxylic acid (e.g., U.S. Pat. 4,971,598 and British Patent GB 2,140,81 1);
Hydroxy-protected chlorodicarbonyloxy compound (e.g., U.S. Pat. No. 4,614,522);
Lactam, thiolactam, thiolactone or ditholactone (e.g., U.S. Pat. Nos. 4,614,603 and 4,666,460);
Cyclic carbonate or thiocarbonate, linear monocarbonate or plycarbonate, or chloroformate (e.g., U.S. Pat. Nos. 4,612,132; 4,647,390; 4,646,860; and 4,670,170);
Nitrogen-containing carboxylic acid (e.g., U.S. Pat. No. 4,971,598 and British Patent GB 2,440,811);
Hydroxy-protected chlorodicarbonyloxy compound (e.g., U.S. Pat. No. 4,614,522);
Lactam, thiolactam, thiolactone or dithiolactone (e.g., U.S. Pat. Nos. 4,614,603, and 4,666,460);
Cyclic carbamate, cyclic thiocarbamate or cyclic dithiocarbamate (e.g., U.S. Pat. Nos. 4,663,062 and 4,666,459);
Hydroxyaliphatic carboxylic acid (e.g., U.S. Pat. Nos. 4,482,464; 4,521,318; 4,713,189);
Oxidizing agent (e.g., U.S. Pat. No. 4,379,064);
Combination of phosphorus pentasulfide and a polyalkylene polyamine (e.g., U.S. Pat. No. 3,185,647);
Combination of carboxylic acid or an aldehyde or ketone and sulfur or sulfur chloride (e.g., U.S. Pat. Nos. 3,390,086; 3,470,098);
Combination of a hydrazine and carbon disulfide (e.g. U.S. Pat. No. 3,519,564);
Combination of an aldehyde and a phenol (e.g., U.S. Pat. Nos. 3,649,229; 5,030,249; 5,039,307);
Combination of an aldehyde and an O-diester of dithiophosphoric acid (e.g., U.S. Pat. No. 3,865,740);
Combination of a hydroxyaliphatic carboxylic acid and a boric acid (e.g., U.S. Pat. No. 4,554,086);
Combination of a hydroxyaliphatic carboxylic acid, then formaldehyde and a phenol (e.g., U.S. Pat. No. 4,636,322);
Combination of a hydroxyaliphatic carboxylic acid and then an aliphatic dicarboxylic acid (e.g., U.S. Pat. No. 4,663,064);
Combination of formaldehyde and a phenol and then glycolic acid (e.g., U.S. Pat. No. 4,699,724);
Combination of a hydroxyaliphatic carboxylic acid or oxalic acid and then a diisocyanate (e.g. U.S. Pat. No. 4,713,191);
Combination of inorganic acid or anhydride of phosphorus or a partial or total sulfur analog thereof and a boron compound (e.g., U.S. Pat. No. 4,857,214);
Combination of an organic diacid then an unsaturated fatty acid and then a nitrosoaromatic amine optionally followed by a boron compound and then a glycolating agent (e.g., U.S. Pat. No. 4,973,412);
Combination of an aldehyde and a triazole (e.g., U.S. Pat. No. 4,963,278);
Combination of an aldehyde and a triazole then a boron compound (e.g., U.S. Pat. No. 4,981,492);
Combination of cyclic lactone and a boron compound (e.g., U.S. Pat. Nos. 4,963,275 and 4,971,711).
The compositions of this invention are compatible with fluorocarbon elastomer seals, at concentrations at which they are effective as detergent and dispersant additives in lubricating oils. When employed in this manner, the modified polyamino alkenyl or alkyl succinimide additive is usually present in from 1 to 5 percent by weight (on a dry polymer basis) to the total composition and preferably less than 3 percent by weight (on a dry or actives polymer basis). Dry or actives basis indicates that only the active ingredient of this invention are considered when determining the amount of the additive relative to the remainder of a composition (e.g., lube oil composition, lube oil concentrate, fuel composition or fuel concentrate). Diluents and any other inactives are excluded. Unless otherwise indicated, in describing the lubricating oil and final compositions or concentrates, dry or active ingredient contents are intended with respect to the polyalkylene succinimides. This includes the novel polyalkylene succinimides of the present invention and also other reaction product or byproducts in the reaction product mixture which function as dispersants.
The lubricating oil used with the additive compositions of this invention may be mineral oil or synthetic oils of lubricating viscosity and preferably suitable for use in the crankcase of an internal combustion engine. Crankcase lubricating oils typically have a viscosity of about 1300 cSt at 0xc2x0 F. (xe2x88x9217.8xc2x0 C.) to 22.7 cSt at 210xc2x0 F. (99xc2x0 C.). The lubricating oils may be derived from synthetic or natural sources. Mineral oil for use as the base oil in this invention includes paraffinic, naphthenic and other oils that are ordinarily used in lubricating oil compositions. Synthetic oils include both hydrocarbon synthetic oils and synthetic esters. Useful synthetic hydrocarbon oils include liquid polymers of alpha olefins having the proper viscosity. Especially useful are the hydrogenated liquid oligomers of C6 to C12 alpha olefins such as 1-decene trimer. Likewise, alkyl benzenes of proper viscosity such as didodecyl benzene can be used. Useful synthetic esters include the esters of both monocarboxylic acid and polycarboxylic acids as well as monohydroxy alkanols and polyols. Typical examples are didodecyl adipate, pentaerythritol tetracaproate, di-2-ethylhexyl adipate, dilaurylsebacate and the like. Complex esters prepared from mixtures of mono and dicarboxylic acid and mono and dihydroxy alkanols can also be used.
Blends of hydrocarbon oils with synthetic oils are also useful. For example, blends of 10 to 25 weight percent hydrogenated 1-decene trimmer with 75 to 90 weight percent 150 SUS (100xc2x0 F.) mineral oil gives an excellent lubricating oil base.
Other additives which may be present in the formulation include detergents (overbased and non-overbased), rust inhibitors, foam inhibitors, corrosion inhibitors, metal deactivators, pour point depressants, antioxidants, wear inhibitors, zinc dithiophosphates and a variety of other well-known additives.
It is also contemplated the modified succinimides of this invention may be employed as dispersants and detergents in hydraulic fluids, marine crankcase lubricants and the like. When so employed, the modified succinimide is added at from 0.1 to 5 percent by weight (on a dry polymer basis) to the oil, and preferably at from 0.5 to 5 weight percent (on a dry polymer basis).
Additive concentrates are also included within the scope of this invention. The concentrates of this invention usually include from 90 to 10 weight percent of an organic liquid diluent and from 10 to 90 weight percent (on a dry polymer basis) of the additive of this invention. Typically, the concentrates contain sufficient diluent to make them easy to handle during shipping and storage. Suitable diluents for the concentrates include any inert diluent, preferably an oil of lubricating viscosity, so that the concentrate may be readily mixed with lubricating oils to prepare lubricating oil compositions. Suitable lubricating oils which can be used as diluents typically have viscosities in the range from about 35 to about 500 Saybolt Universal Seconds (SUS) at 100xc2x0 F. (38xc2x0 C.), although an oil of lubricating viscosity may be used.
Typically the fuel composition will about from 10 to 10,000 weight parts per million, preferably from 30 to 2,000 weight parts per million, of base fuel. This is based on active ingredient including the other dispersant reaction products as well as the compounds of formula (I) but excluding inactives for example diluent oil and any unreacted alkene or poly xcex1-olefins etc. carried through from the preparation of succinic anhydride (A) or copolymer (B). If other detergents are present, a lesser amount of the modified succinimide may be used. Optimum concentrations can vary with the particular base oil and the presence of other additives, but, can be determined by routine procedures.
The compositions of this invention may also be formulated as a fuel concentrate, using an inert stable oleophilic organic solvent boiling in the range of about 150xc2x0 F. to 400xc2x0 F. Preferably, an aliphatic or an aromatic hydrocarbon solvent is used, such as benzene, toluene, xylene or higher-boiling aromatics or aromatic thinners. Aliphatic alcohols of about 3 to 8 carbon atoms, such as isopropanol, isobutylcarbinol, n-butanol and the like, in combination with hydrocarbon solvents are also suitable for use with the fuel additive. The present fuel concentrate will typically contain about from 20 to 60 wt. % of the present composition or an active ingredient basis.